In virtual machine environments, the file system workload typically involves a relatively small number of large files (e.g., virtual disk files), to which reads and writes are the primary operations. In many cases, only a relatively small part of the data comprising a virtual disk is being written to and/or read at any one time.
In tiered storage systems, i.e., those that include two or more different types of storage device and/or media, decisions to switch between different tiers of storage typically have been made based on the different speeds of accessing data for each of the tiers of the storage. For example, in typical multi-tiered storages involving flash and hard disk storages, the flash storage may used for caching purposes, due to its relatively fast access times, while the disk storage is used for more long-term storage. In a typical tiered storage system, storage parameters such as block size are determined to optimize performance and/or accommodate a limitation of one or the other of the types of storage, and the same parameter is used for both types of storage.